Autobiography of Sir George Biddell Airy

by George Biddell Airy

1855

"On May 9th it was notified to me (I think through the Hydrographer) that the Admiralty were not unwilling to increase my salary. I made application therefore; and on Jan. 21st 1856 Sir Charles Wood notified to me that the Admiralty consented to have it raised from £800 to £1000.—In the Report to the Board of Visitors it appears that 'At the instance of the Board of Trade, acting on this occasion through a Committee of the Royal Society, a model of the Transit Circle (with the improvement of perforated cube, &c. introduced in the Cape Transit Circle) has been prepared for the Great Exhibition at Paris.'—Under the head of Reduction of Astronomical Observations it is stated that 'During the whole time of which I have spoken, the galvanic-contact method has been employed for transits, with the exception of a few days, when the galvanic apparatus was out of order. From the clock errors, I have deduced the personal equations of the observers in our usual way…. The result is that the magnitude of the personal equations in the galvanic-touch method is not above half of that in the eye and ear method.'—With regard to the Reduction of the Magnetical Observations, 'I have not yet felt sufficiently satisfied with any proposed method of discussing the magnetic results to devote any time to their further treatment.'—'The Time-Signal Ball at Deal was brought into regular use at the beginning of the present year. In a short time, however, its action was interrupted, partly by derangement of the apparatus, and partly by the severity of the weather, which froze the sulphuric acid to the state of jelly. I sent an assistant and workman to put it in order, and since that time it has generally acted very well.—Application has been made to me from one of the important offices of Government (the Post Office) for the galvanic regulation of their clocks.—On considering the risks to which various galvanic communications are liable, and the financial necessity for occupying wires as little as possible, I perceived that it was necessary to devise constructions which should satisfy the following conditions. First, that a current sent once a day should suffice for adjusting the clock, even if it had gone ten or more seconds wrong. Secondly, that an occasional failure of the current should not stop the clock. I have arranged constructions which possess these characters, and the artist (Mr C. Shepherd) is now engaged in preparing estimates of the expense. I think it likely that this may prove to be the beginning of a very extensive system of clock regulation."—With respect to the operations for determining the longitude of Paris, it is stated that, "The whole number of days of signal transmission was eighteen, and the whole number of signals transmitted was 2530. The number of days considered available for longitude, in consequence of transits of stars having been observed at both Observatories, was twelve, and the number of signals was 1703. Very great care was taken on both sides, for the adjustments of the instruments. The resulting difference of longitude, 9m. 20.63s., is probably very accurate. It is less by nearly 1s. of time than that determined in 1825 by rocket-signals, under the superintendance of Sir John Herschel and Col. Sabine. The time occupied by the passage of the galvanic current appears to be 1/12th of a second."—With regard to the Pendulum Experiments in the Harton Colliery, after mentioning that personal assistance had been sought and obtained from the Observatories of Cambridge, Oxford, Durham, and Red Hill, the Report states that "The experiments appear to have been in every point successful, shewing beyond doubt that gravity is increased at the depth of 1260 feet by 1/10000th part. I trust that this combination may prove a valuable precedent for future associations of the different Observatories of the kingdom, when objects requiring extensive personal organization shall present themselves."—On Oct. 18th the Astronomer Royal printed an Address to the Individual Members of the Board of Visitors on the subject of a large new Equatoreal for the Observatory. After a brief statement of the existing equipment of the Observatory in respect of equatoreal instruments, the Address continues thus: "It is known to the Visitors that I have uniformly objected to any luxury of extrameridional apparatus, which would materially divert us from a steady adherence to the meridional system which both reason and tradition have engrafted on this Observatory. But I feel that our present instruments are insufficient even for my wishes; and I cannot overlook the consideration that due provision must be made for future interests, and that we are nearer by twenty years to the time when another judgment must decide on the direction which shall be given to the force of the Observatory."—"In August I had some correspondence about the Egyptian wooden astronomical tablets with Mr Gresswell and others: they were fully examined by Mr Ellis.—In this year I was much engaged on schemes for compasses, and in June I sent my Paper on Discussions of Ships' Magnetism to the Royal Society.—On Dec. 6th the mast of the Observatory time-ball broke, and the Ball fell in the Front Court.—On Aug. 4th my valued friend Mr Sheepshanks died; and on Aug. 14th I went to London to see the Standard Bars as left by him. Afterwards, on Oct. 25th I went to Reading to collect the papers about Standards left by Mr Sheepshanks.—I made a mechanical construction for Euclid I. 47, with which I was well satisfied.—On Apr. 13th I joined a deputation to the Chancellor of the Exchequer (Sir G. Cornewall Lewis) on Decimal Coinage."

Of private history: "I was at Playford for a large part of January.—On Mar, 26th I went to Reading, to visit Mr Sheepshanks, and afterwards to Silchester and Hereford.—On June 21st I went with my wife and two eldest sons to Edinburgh and other places in Scotland, but residing principally at Oban, where I hired a house. Amongst other expeditions, I and my son Wilfrid went with the 'Pharos' (Northern Lights Steamer) to the Skerry Vohr Lighthouse, &c. I also visited Newcastle, &c., and returned to Greenwich on Aug. 2nd.—From Oct. 12th to 17th I was at Cambridge.—On Dec. 24th I went to Playford."

CHAPTER VII.

AT GREENWICH OBSERVATORY—1856 TO 1866.

1856

"In the Report to the Visitors there is an interesting account of the difficulties experienced with the Reflex Zenith Tube in consequence of the tremors of the quicksilver transmitted through the ground. Attempts were made to reduce the tremor by supporting the quicksilver trough on a stage founded at a depth of 10 feet below the surface, but it was not in the smallest degree diminished, and the Report states that 'The experience of this investigation justifies me in believing that no practicable depth of trench prevents the propagation of tremor when the soil is like that of Greenwich Hill, a gravel, in all places very hard, and in some, cemented to the consistency of rock.'—With respect to the regulation of the Post Office clocks, 'One of the galvanic clocks in the Post Office Department, Lombard Street, is already placed in connection with the Royal Observatory, and is regulated at noon every day … other clocks at the General Post Office are nearly prepared for the same regulation, and I expect that the complete system will soon be in action.'—Under the head of General Remarks a careful summary is given of the work of the Observatory, and the paragraph concludes as follows: 'Lastly there are employments which connect the scientific Observatory with the practical world; the distribution of accurate time, the improvement of marine time-keepers, the observations and communications which tend to the advantage of Geography and Navigation, and the study, in a practical sense, of the modifications of Magnetism; a careful attention to these is likely to prove useful to the world, and conducive to the material prosperity of the Observatory: and these ought not to be banished from our system.'—In September I prepared the first specification for the building to carry the S.E. Dome.—In September, learning that Hansen's Lunar Tables were finished in manuscript, I applied to Lord Clarendon and they were conveyed to me through the Foreign Office: in October I submitted to the Admiralty the proposal for printing the Tables, and in November I learned that the Treasury had assented to the expense.—Lieut. Daynou's eclipses and occultations for longitudes of points in South Africa, observed in 1854 and 1855, were calculated here in this year.—On Feb. 16th I made my first application to Sir C. Wood (First Lord of the Admiralty) for assistance to C. Piazzi Smyth to carry out the Teneriffe Experiment: grounding it in part on the failure of attempts to see the solar prominences. He gave encouragement, and on Mar. 18th I transmitted Piazzi Smyth's Memorial to the Admiralty: on May 2nd the Admiralty authorized an expense of £500. I drew up suggestions.—The Sheepshanks Fund: After the death of my friend Richard Sheepshanks, his sister Miss Anne Sheepshanks wished to bestow some funds in connection with the University of Cambridge, Trinity College, and Astronomy, to which his name should be attached. There must have been some conversation with me, but the first letter is one from De Morgan in August. In September I had a conversation with Miss Sheepshanks, and sent her my first draft of a scheme, to which she assented. On Sept. 30th I wrote to Whewell (Master of Trinity) who was much trusted by Miss Sheepshanks: he consented to take part, and made some suggestions. There was further correspondence, but the business did not get into shape in this year.—In connection with the Correction of the Compass in Iron Ships: I discussed the observations made in the voyage of the Royal Charter. On Feb. 13th I proposed to the Admiralty a system of mounting the compasses with adjustable magnets, and it was ordered to be tried in the Trident and Transit.—In February I reported to the Admiralty that the Deal Time-Ball had been successful, and I proposed time-balls at Portsmouth, Plymouth, and Sheerness. There was much correspondence in various directions about Portsmouth and Devonport, and in March I went to Devonport and specially examined Mount Wise and the Devonport Column.—I had correspondence with Sir Howard Douglas about the sea breaking over the unfinished Dover Pier. I have an idea that this followed evidence given by me to a Harbour Commission, in which I expressed as a certainty that the sea will not be made to break by a vertical wall."

Of private history: "I returned from Playford on Jan. 18th.—From June 16th to August 5th I was, with my son Wilfrid, on an expedition to South Italy and Sicily: on our return from Sicily, we remained for three days ill at Marseilles from a touch of malaria.—On Dec. 22nd I went to Playford.—In acknowledgment of the pleasure which I had derived from excursions in the Cumberland Passes, I made a foot-bridge over a troublesome stream on the Pass of the Sty Head."

1857

"In the Report to the Visitors, when on the subject of the Altazimuth, the following paragraph occurs: 'I alluded in a preceding section to the cutting away of a very small portion of one of the rays of the three-armed pier which carries the Altazimuth. The quality of the brickwork is the best that I have ever seen, and not a single brick was disturbed beyond those actually removed. Yet the effect was to give the Altazimuth an inclination of about 23". This inclination evidently depends on the elasticity of the brickwork.'—With reference to the new S.E. Equatoreal the Report states that 'The support of the north or upper end of the polar axis has been received, and is planted within the walls of the building in a position convenient for raising it to its ultimate destination. It is one piece of cast-iron, and weighs nearly 5 tons.'—Small changes as previously mentioned had been noticed with regard to the Zero of Azimuth of the Transit Circle, and the Report states that 'In regard to the Azimuth of the Transit Circle, and the Azimuth of its Collimator, Mr Main has brought together the results of several years, and the following law appears to hold. There is a well-marked annual periodical change in the position of the Transit Circle, the southerly movement of the eastern pivot having its minimum value in September, and its maximum in March, the extreme range being about 14 seconds; and there is a similar change, but of smaller amount, in the position of the Collimator. I cannot conjecture any cause for these changes, except in the motion of the ground. There is also a well-marked connection between the state of level of the axis and the temperature. The eastern pivot always rises when the temperature rises, the extreme range being about 6 seconds. I cannot offer any explanation of this.'—Under the head of Extraneous Works the Report states that 'The British Government had for some years past contributed by pecuniary grants to the preparation of Prof. Hansen's Lunar Tables. In the last winter they undertook the entire expense of printing a large impression of the Tables. The reading of the proof-sheets (a very considerable labour) has been effected entirely at the Observatory. I may take this opportunity of stating that the use of these Tables has enabled me, as I think, incontestably to fix the capture of Larissa to the date B.C. 557, May 19. This identification promises to prove valuable, not merely for its chronological utility, but also for its accurate determination of an astronomical epoch, the point eclipsed being exactly known, and the shadow having been very small.'—In April I gave a lecture to the Royal Astronomical Society on the methods available through the next 25 years for the determination of the Sun's parallax.—Dr Livingstone's observations for African longitudes were computed at the Observatory.—The Admiralty enquire of me about the feasibility of adopting Piazzi Smyth's construction for steadying telescopes on board ship: I gave a Report, of mixed character, on the whole discouraging.—I had correspondence with G.P. Bond and others about photographing the Stars and Moon.—On Feb. 17th Piazzi Smyth's books, &c. relating to the Teneriffe Experiment were sent to me: I recommended that an abridged Report should be sent to the Royal Society.—Respecting the Sheepshanks Fund: there was correspondence with Miss Sheepshanks and Whewell, but nothing got into shape this year: Miss Sheepshanks transferred to me £10,000 lying at Overend and Gurney's.—In November experiments were made for the longitude of Edinburgh, which failed totally from the bad state of the telegraph wire between Deptford and the Admiralty.—In June the first suggestion was made to me by Capt. Washington for time-signals on the Lizard Point: which in no long time I changed for the Start Point.—The Admiralty call for estimates for a time-ball at Portsmouth: on receiving them they decline further proceeding.—I was engaged in speculations and correspondence about the Atlantic Submarine Cable.—In the Royal Astronomical Society, I presented Memoirs and gave lectures on the three great chronological eclipses (Agathocles, Thales, Larissa)."—On Dec. 5th Airy wrote to the Vice-Chancellor of the University of Cambridge, objecting to the proposed changes regarding the Smith's Prizes—a subject in which he took much interest, and to which he ascribed great importance.—On Apr. 27th I was in correspondence with G. Herbert of the Trinity House, about floating beacons.—In July I reported to the Treasury on the Swedish Calculating Engine (I think on the occasion of Mr Farr, of the Registrar-General's Office, applying for one).—In November I had correspondence about the launch of the Great Eastern, and the main drainage of London."